The invention relates to methods for authenticating objects, and in particular, relates to methods for embedding security data into products, and methods for authenticating these products using the embedded security data.
Counterfeiting and piracy have a huge economic impact. While numerous product security features have been developed, there remains a demand for cost effective security measures that inhibit counterfeiting and piracy.
Research in the field of steganography (also called xe2x80x9cdata hidingxe2x80x9d) offers promising technology for combating counterfeiting and piracy. One form of steganography is referred to in popular literature as digital watermarking. Digital watermarking is a process for modifying a host signal or object to embed a machine-readable code into the host. The host may be modified such that the embedded code is imperceptible or nearly imperceptible to the ordinary observer upon viewing or playback, yet may be detected through an automated detection process.
Most commonly, digital watermarking is applied to media such as images, audio signals, and video signals. However, it may also be applied to other types of media, including documents (e.g., through subtle line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
The invention relates to methods for authenticating printed objects using digital watermarks embedded in the images on the objects. One aspect of the invention is a system for authenticating a printed object. The system includes a watermark decoder and a verification module. The watermark decoder detects a copy detection watermark in a printed object to determine whether the printed object has been reproduced. The verification module processes a message decoded from an authentication watermark on the printed object to authenticate the printed object or bearer of the printed object. The authentication and copy detection watermarks may be implemented as the same or different watermarks. For example, the copy detection watermark may be a fragile watermark that carries the message and that degrades in response to a reproduction operation, such as photocopying or scanning and then re-printing the object. Alternatively, the authentication and copy detection watermarks may be separate watermarks embedded in an image that is printed on the object. The authentication watermark, in some applications, includes an identifier that links the object to a database entry with related information about the object. This related information can be used to check the bearer of the object by comparing it with attributes of the bearer (such as a user ID or photo) or the validity of the object by comparing it with attributes that are visible or machine readable on the object.
Another aspect of the invention is a system for creating a printed object. The system includes a watermark encoder and communication application. The watermark encoder encodes a watermark in an image to be printed on a printed object. This watermark is used to authenticate the printed object. The communication application obtains an identifier from a database for embedding into a message payload of the watermark. It also provides to the database information to be associated with the identifier.
Further features will become apparent with reference to the following detailed description and accompanying drawings.